FAO calls for minimum tillage to halt soil erosion

Ploughing can be bad for the soil. A minority of
agriculturalists have been saying so for years and FAO is
now adding its voice to the call for a drastic reduction in
tillage in order to slow land degradation around the
world.

Both
mechanized and animal tillage can lead to soil
loss

According to the Organization, "with the advent of
tractors, the tendency was to increase tillage and farmers
started to believe that the more you till the soil, the more
yield you get. The truth is that more tillage causes more
erosion and soil degradation, especially in warmer areas
where the topsoil layer is thinner." Today's conventional
ploughing methods cause severe soil loss and desertification
in many developing countries. FAO estimates that some 40
percent of land degradation around the world is caused by
soil erosion.

The Organization has issued a dramatic warning to
farmers: "Parts of Latin America and Africa could become
dust-bowls if farmers don't change their tillage practices.
Every time a farmer tills land to control weeds, the soil
becomes more vulnerable to erosion and the soil structure is
destroyed. Conventional tillage with tractors and ploughs
provokes soil compaction and biological degradation. Even
animal traction systems, to a lesser extent, can lead to
erosion. The way soils are cultivated today needs to be
drastically changed."

FAO is holding a workshop to promote conservation tillage
in Harare, Zimbabwe, from 22 to 27 June. The meeting will
begin work on the formulation of a code of conduct on soil
management and the outline of a regional project on
conservation tillage will be prepared. The German Agency for
Technical Cooperation (GTZ), the South African Research
Council, a Swedish-funded FAO project and the Zimbabwe
Farmers Union will participate in the meeting.

In Latin America, RELACO, a network promoting
conservation tillage, was established in 1992 and more than
14 million hectares of farmland in the region are now under
zero-tillage - in which the soil is disturbed only where the
seed is planted. One of the tools specially designed for
this is the chisel plough.

In Africa, minimum tillage is mainly practised only on
large estates, but the regional project will be targeting
smallholders too. Significantly for smaller farmers, minimum
tillage also cuts the costs of land preparation. For
example, production costs per acre for soybeans could be cut
by US$27 in Argentina, US$14 in the United States and US$11
in Brazil, by introducing minimum tillage techniques.

According to FAO expert José Benites of the Soil
Resources Management and Conservation Service, soils in
tropical countries do not normally need to be tilled. "The
most desirable form of tillage is conservation tillage which
leaves a protective blanket of leaves, stems and stalks from
the previous crop on the surface. This cover shields the
soil surface from heat, wind and rain, keeps the soil cooler
and reduces moisture loss by evaporation."